1. Field of the Invention
The present invention relates to a method used in a wireless communication system and related communication device, and more particularly, to a method of handling a transferring from an energy-consuming mode to an energy-saving mode and related communication device.
2. Description of the Prior Art
As more and more network applications (e.g., voice over IP (VoIP), instant messaging, web browsing, etc.) are built or installed in a communication device in nowadays, a large amount of energy is consumed when performing the network applications. A lifetime of a battery in the communication device is greatly reduced, and inconvenience is caused to a user of the communication device. Thus, energy efficiency becomes a key issue for the communication device.
For example, a timer (e.g., inactive timer) is considered in the prior art, to improve the energy efficiency. In detail, operation modes of the communication device are divided into an energy-consuming mode (e.g., active mode, connected mode) and an energy-saving mode (e.g., idle mode, sleep mode). Before the communication device starts to communicate with a network (i.e., transmits or receives messages/packets), the communication device transfers to the energy-consuming mode to receive necessary control signalings and perform necessary initialization procedures (e.g., registration, random access, etc.). Then, the communication device stays in the energy-consuming mode to keep communicating with the network, so as to perform the network applications. If the communication device stops communicating with the network (e.g., stop transmitting and receiving the messages) in the energy-consuming mode, the timer is activated (i.e., starts running). If the timer expires, the communication device determines that no network application is performed and transfers to the energy-saving mode. Thus, the communication device can save the energy to improve the lifetime of the battery. Otherwise, if the communication device communicates with the network again, the timer is stopped and reset.
In this situation, it is important to configure a value of the timer properly. For example, if the value is too small and the communication device does not really finish the network applications, the communication device needs to transfer back to the energy-consuming mode to communicate with the network. Then, it is possible that the communication device transfers between the energy-consuming mode and the energy-saving mode frequently, and energy of the battery is wasted due to frequent transferring. Oppositely, if the value is too large and the communication device has finished the network applications, the communication device will stay in the energy-consuming mode for a long time before the timer expires. Thus, the energy is wasted due to that the communication device continues to receive the control signalings and perform related procedures. Besides, since the network applications performed by the communication device are diverse, properties such as frequencies of performing the network applications, durations within which the network applications are performed, amounts of messages (e.g., signalings) generated by the network applications, etc., are also diverse. Thus, it is difficult to configure the value of the timer properly. How to save the energy efficiently is thus a topic to be discussed.